浅埋深黏土包气带氮迁移转化原位实验研究

Movement and transformation of nitrogen in clay unsaturated zone under shallow groundwater table:In-situ experiment

通过原位实验,对浅埋深黏土包气带中氮的迁移转化开展研究.结果表明,实测地下水埋深介于145.9~173.6cm,地下水毛细上升高度计算值可达297.0cm,土壤含水率除表层外介于0.30~0.45cm^(3)/cm^(3);NH_(4)^(+)-N和NO_(3)^(-)-N在地面以下155cm含量最高为1.43,23.00mg/kg,超出背景值1.13,21.05mg/kg;包气带含水率近饱和条件下,粘土对氮污染物迁移阻滞作用减弱,NH_(4)^(+)-N和NO_(3)^(-)-N在1d内自地表迁移至155cm.浅埋深地下水减弱了黏土对氮污染物运移的阻滞作用.浅埋深地下水减弱了黏土对氮污染物运移的阻滞作用.

In this paper,the movement and transformation of nitrogen was investigated in clay unsaturated zone with shallow groundwater depth via in-situ experiment.Results show that,The depth to groundwater table fluctuated between 145.9cm and 173.6cm,and the calculated capillary height of groundwater reaches 297.0cm which induces high soil water content in soil profile,varied between 0.30~0.45cm^(3)/cm^(3) except for near surface layer;The concentration of NH_(4)^(+)-N and NO_(3)^(-)-N was of the maximum value at 155cm depth in the soil profile,1.43 and 23.00mg/kg,respectively,which exceeded the background values of 1.13 and 21.05mg/kg;Under the condition of nearly saturated of the clay soil,the NH_(4)^(+)-N and NO_(3)^(-)-N moved from ground surface to the depth of 155cm within one day.The research results indicated that the blocking effect of clay on the movement of nitrogen pollutants is weakened on shallow groundwater table depth.